US1798840A - Pigmented lacquer base - Google Patents

Description

Patented Mar. '31, 1931 l HENRY J. GWAY AND WILLIAM A. WEIDLICH, OF BOUND BROOK, NEW. JERSEY V rrennnrnn nacounn nasn 1T0 Drawing. I Application filed October 13, 1830. Serial No. 488,548.

- This invention relates to a novel method larly in the case of lacquer enamels upon the of preparing pigmented lacquer bases and addition of solvents, such as ethyl acetate to primarily has for its object obtaining a lacthe pigmented nitrocellulose, flocculation is quer-base of a type possessing superlative inevitable, and the original more or less satisv 5 quality in fineness, texture and uniformity factory-dispersion in the aqueous fluid is de- 55 of pigmentation, while also effecting great stroyed in part or in whole by flocculation.

economies, over present practices, in the man- Accordingly, a distinctive and principal ufacture of the new product. object of the present invention is th t of uti- Heretofore in the practical manufacture lizing amethod of procedure, in the preparaof pigmented lacquer bases one of the operation of apigmented lacquer base,- which en- '60 tions which has been considered indispensatirely eliminates the use of grinding machin ble is that of a thoroughly grinding the pre cry and grinding operations of any kind, formed pigmentpreliminary to or upon its while at the same time insuring optimum introduction into the film forming constitudispersion of the pigment without the necuts, the grinding operation frequently occu cessity 'of preliminary aqueous dispersion 65 pying periods of from twenty four'to one. and with a minimum expenditure of energy. hundred hours to reduce the pigment to a Thus the time element in themaking of thesuflicient fineness to make a satisfactorftl lacquer base is .very greatly shortened and product, as well as to bring about a thorou the use of'extensive grinding machinery ob wetting of the pigment, with the liqui s. viated, while at the same time in the case 7 A great amount of time is required for these of pigments upon a soluble cellulosic base, grinding operations and with a large nuina pigmented product is evolved of such a, ber of different pigments to be considered, a character and in such physical condition that very heavy outlay of capital is required to solvents may later be added in the manufacsupply and maintain separate grinding ture of the finished lacquer without again 75 equipment for the difl'erent pigments; destroying the dispersion by reagglomera- Furthermore, this preliminary grinding tion orb flocculation, 1 m step for pigments, as heretofore practiced, There ore, a feature of practical imporalso has had, as indicated, assigned to it the tance in car ing forward the invention is function of bringing about athor'ough wet- .that of rovi in a process which effectually 8 ting of the pigment which has anatural ph sbreaks o wn alagglomeration and so conical repulsion for the liquid media which trols the viscosityor internal 'friction that' must be overcome by continued and extensive at no time during the process of manufacgrinding in the presence of the wetting me-. 'ture shall the pigment articles. be allowed ia. Some attempts have been made to facil-. to agglomerate or floccuiiite. itate this operation of wetting, and to bring he precise order in which the steps of the about a dispersion of pigments in the wetting process may be carried. out, "as well as the media, by dispersing the pigment in water formulae for the batches,'necessarily are susand then incorporating the .pigmentwith a ceptible of a wide range of modification w1th soluble solid constituent. The whole mass out departing from the spirit or scope of the w is then later dehydrated with alcohol, and "invention and by way of example one sucthat known process is more directly apcessful way of carry ng the invention mto plicable to cases where a color pigment is eflect may'briefly described as follpws:- produced by chemical precipitation upon a For instance, taking commercial n1trocelcellulosic. base. According to that method lulose as the film forming constituent or where an attempt is made to pigment a cellubinder, a formula, b way of example, which -losic base with pigment in a watery media, .may be utilized in t e first stages of the new there is a pronounced tendency during the method would 1nclude:-' 1

subsequent dehydration with alcohol for the Eighty-sirpounds of, p gment (erg. t1- pigmentagain to fiocculate; and, particutanox).

, alcohol-damp 1 Fifteen pounds of alcohol.

Five pounds of ethyl acetate.

Fifteen pounds of nitrocellulose.

Preliminarily, the batch of commercial nitrocellulose which usually is handled in condition has added thereto such an ad tional quantity of alcohol or other suitable non-aqueous liquid, such as xylol, toluol, benzol or equivalent derivatives which will not only completely wet the body of the nitrocellulose, but all the particle surface of such quantity of pigment as the formula calls for.

This first stage of the process includes the mixing and kneading together, in a mixing machine of any approved type, a part1 wetted or dampened nitrocellulose body wit the supplementary addition of alcohol or equivalent chemical until the excess alcohol or equivalent chemical has been taken up by the nitrocellulose by capillarity.

The second stage, of the process being described as one example of the invention, involves the distinctive feature of incorporating the pigment with the film forming constituent ofthe lacquer, and that step consists in adding to the completely wetted ni- .trocellulose mass the entire charge of commercial pigment without emplo grinding. The mixing and knea mg operation goes forward in this second stage of the process producing what ma be termed ent of a pigment tree of nitrocellulose oliated with pigment particles, that is, the pigment particles in this operation becoming uniformly spreadover and upon the surfaces of the nitrocellulose and absorbed thereon. At the same time the nitrocellulose body becomes opened up and simultaneously the pi ment particles will have been completely ampened with the excess non-aqueous li uid utilized in the first stage of preparing t e nitrocellulose.

The next or third stage in the evolution of the described process involves the addition of the remaining diluents, for exam two pounds of alcohol, five pounds of .et acetate and ten poundstoluol and the continuation of the mixing operation in the mixing machine. In this stage of the process the nitrocellulose becomes dissolved, changing from its fibrous state to a continuous phase producing a smooth plastic mass whose viscosity or internal friction 1s controlled so that the pigment particles become reduced agglomeration particles to a fineness or phase to reduce such.

' which is quite impossible through any grind-- ing operation heretofore practiced and to obtam of extreme practical importance because it is depended upon to prevent rethat desirable and important result'th'e viscosity of the mass in the said third stage of the process must be controlled by the presence of only suflicient liquid to maintain an veffective viscosity and not enough liquid to float the pigment particles so as to thereby permit them to flocculate. Because of this viscosity or internal friction, maintained in the manner described, the mass movement of Since industrial use demands a more fluid substance thanj results from the-preceding stage three of the described process, additional solvent is gradually added, with which solvent is blended as large a proportion of alcohol or other suitable diluent as may be used Without permitting reagglomeration.

Thus, itwill be seen from the foregoing description of the example selected that as distinguished from prior methods which rely for satisfactory dispersion of the pigment on the intensity of the grinding it will be seen that the present method does not employ grinding at poration of the dry pigment with damp nitrocellulose in the presence of a non-aqueous liquid, the retention of the pigment particles in a dispersed conditioniby adsorption on the nitrocellulose during the fibrous state, and by retention at all times during the change from fibrous to continuous phase in the nitrocellulose of a high internal resistance or viscosity throughout the mass. Thus, the resent invention accomplishes the desira le objects herein set forth without resorting to grinding for thepigments and without resortmg to a preliminary water dispersion, as heretofore practiced, because according to the present invention as the agglomerates, by friction and shearing break themselves down in the presence of, and intimate contact with, the fibrous structure of the cellulose material, the dispersed particles become evenly distributed along the fibres of said material and so having been once defiocculated the tendency to re flocculate is overcome and the operation of the process is continuous and goes forward from the mixing of the constituents through to the finished product in one machine or mixer of the approved ty e, and optimum dispersion of the pigment y the simple process of a brief mixing operation is accomplished.

,While one mode of practicing the process has been selected to exemplify the invention one time all of the ingredients or constituents against particles and the shearing any stage and relies on the incorlose and pigment.

of the formulae and carrying the mixin or kneading operation forward until the pro not is complete. However, even with that way of carrying out the invention the batch necessarily passes throu h the several phases or stages described, an case of the previously cited example, the essential factor to the success ofthe process involves the retention at andduring each stage of the mix of a condition of high viscosity or internal friction whereby the results previ ously secured by extensive grinding are achieved by and within therefore within the purview of the present invention to resort to changes or modification of the steps of the process or in the order of such steps or in the formulae used without departing from the spirit or scope of the inventlon as set forth in the ap ended a claim, and it is also to be understood t at the present invention is intended to cover a method of preparing a base for the production of lacquer enamels but also is applicable to a preparation of a base for finishing protective or decorative coatings containing nitrocellu- We claim:

An improved method for preparing a pigmented lacquer base which consists in the new step of first subjecting without grinding or rolling pressure a non-aqueous mix of nitrocellulose and unground pigment solely to the kneading action of a mixing machine in the presence of a relatively small quantity of a liquid volatile solvent to initiate the chemical action of dissolving the nitrocellulose simultaneously with the pulverization of the pigment and its dispersion throughout the batch, 1

the said initial quantity of liquid" solvent be ing insuflicient to complete the dissolution of the introcellulose but of an amount to thereby maintain and control a hi during the said kneading action t ereb roducing in the mass while being kneadz an internal attrition of pigment particles against pigment particles causing by such attrition alone the breaking down of the agglomerates and/or flocculates and dispersing the finely divided pigment throughout the film-formin vehicle, and subsequently introducing an working into the mass the remaining predetermined amount of solvent necessary to complete the dissolution of the nitrocellulose to change it into a continuous viscous phase. 1 In testimony whereof wehereunto aflix our signatures.

HENRY J. HIEMINGWAY,

WILLIAM A. WEIDLICH.

in this example, as in the the mass itself. It is h viscosity